| 摘要 |
1,013,608. Printed circuits. SIEMENS & HALSKE A.G. Sept. 21, 1964 [Sept. 19, 1963], No. 38408/64. Heading H1R. In a process for making a printed circuit, an insulating plate 1, Fig. 3, is provided with an adhesive layer 3, a basic metal layer 4, and a negative stencil 5; the exposed portions of the metal layer 4 are electrolytically thickened to form conductors 2, and the conductors 2 and stencil 5 are covered with a protective layer 6 which is insoluble in the solvent to be used to remove the stencil. The stencil 5 is dissolved away (a portion of the protective layer being uncovered to allow the solvent access), and the parts of the protective layer 6 covering the stencil are removed at the same time or subsequently. The unthickened parts of the metal layer 4 are etched away to form a printed circuit, Fig. 6, having conductors 2 protected by layer 6; alternatively, layer 6 may be removed from the conductors 2 after the etching step. The initial metal-clad insulating plate maybe formed by the process of Specification 1,013,606, or a copper-clad laminate or an insulating plate sprayed with metal may be used. The stencil 5, which may be applied by screen printing, may have a base of colophony- . modified linseed oil, and the protective layer 6 may be shellac applied by spraying, brushing or printing. Conductors 2 may be of copper, and may be covered, with silver or a tin-lead alloy. |
